FRICTION AND WEAR OF DIAMOND-LIKE CARBON-FILMS DEPOSITED USING DIFFERENT METHODS UNDER DIFFERENT CONDITIONS

Diamondlike carbon (DLC) films were deposited on Si and WC-Co alloys u sing radio-frequency plasma-assisted chemical vapor deposition (CVD) a nd physical vapor deposition (PVD), respectively. The resulting DLC fi lms had a friction coefficient of less than 0.1 and a specific wear ra te of the order of 10(-7) mm(3)/Nm in dry air; friction and wear were negligibly affected, either by the deposition method or by the substra te material in the present study. The friction coefficient of DLC film s deposited on Si by CVD depended neither on substrate bias voltage no r on CH, gas pressure. When DLC films were rubbed against a SiC ball, the critical load at which the friction coefficient increased abruptly depended on the substrate bias voltage; the critical load for films d eposited at -100 V was larger than that for films deposited at other b ias voltages. The critical load also appeared to be correlated with th e DLC film hydrogen content. CH, gas pressure, in contrast, had almost no effect on critical load in the present study. The friction coeffic ient in humid air was appreciably higher than in dry air.